On Tue, Apr 23, 2024 at 05:38:41AM +0100, Matthew Wilcox wrote:
> What would you think to this?
>
> +++ b/include/linux/delayed_call.h
> @@ -14,13 +14,12 @@ struct delayed_call {
>
> #define DEFINE_DELAYED_CALL(name) struct delayed_call name = {NULL, NULL}
>
> -/* I really wish we had closures with sane typechecking... */
> -static inline void set_delayed_call(struct delayed_call *call,
> - void (*fn)(void *), void *arg)
> -{
> - call->fn = fn;
> - call->arg = arg;
> -}
> +/* Typecheck the arg is appropriate for the function */
> +#define set_delayed_call(call, _fn, _arg) do { \
> + (void)sizeof(_fn(_arg)); \
> + (call)->fn = (void (*)(void *))(_fn); \
> + (call)->arg = (_arg); \
> +} while (0)
>
> static inline void do_delayed_call(struct delayed_call *call)
> {
>
>
> That should give us the possibility of passing any pointer
> to the function, but gets us away from void pointers. I did this as a
This just means KCFI will freak out now, since it will see a mismatch
between call->fn's type and the target function's type. :(
And instead of args like this, can't we use the regular container_of()
tricks to get at the pointer we want? i.e. make "call" a member of the
strut doing the delayed call?
-Kees
> followup:
>
> -extern void page_put_link(void *);
> +extern void page_put_link(struct folio *);
>
> ...
>
> -void page_put_link(void *arg)
> +void page_put_link(struct folio *folio)
> {
> - put_page(arg);
> + folio_put(folio);
> }
> EXPORT_SYMBOL(page_put_link);
>
> and similar changes to the three callers.
>
> Or is there something newer and shinier we should be using instead of
> delayed_call?
--
Kees Cook
